Dental restorations or prostheses are often made as a configuration of two or more components, with the individual components providing different characteristics for the restoration. For example, a framework may provide good structural support, and a veneer may provide good aesthetics. The framework generally is a supporting structure for the dental restoration that provides mechanical stability and usually comprises an interface by which the restoration can be affixed to a prepared tooth of a patient. The veneer provides for pleasing aesthetic characteristics so that the restoration resembles a natural tooth in shape and appearance. In addition, both the frame and the veneer are shaped to fit well with the adjacent and opposed teeth in a patient's mouth.
In recent years ceramic materials have been widely used for making high-quality dental restorations because of their good physical, aesthetic and biological properties. In some applications such dental restorations are made by combining a ceramic framework and a ceramic veneer. The framework and the veneer may, for example, be ground or milled from a ceramic blank, or cast from a molten ceramic material. It is desirable that the dental restoration also has an appearance that matches or approximates the appearance of adjacent teeth.
The dental restoration is typically manufactured based on a physical and/or digital replication of the tooth to be restored and adjacent teeth. For example the relevant teeth may be captured physically by a dental impression and/or digitally by scanning the teeth, or a model obtained from the dental impression. A dentist typically provides such physical and/or digital replication to a dental technician who uses that replication to manufacture an appropriate dental restoration. The dental restoration may then be sent to the dentist for implantation in the patient's mouth.
The dental technician is typically provided with all information necessary to complete the dental restoration so that, once such information is obtained from the patient, the dental restoration can be manufactured independently from the patient. Therefore such information typically also includes information about the shape of the tooth prepared to receive the dental restoration, which can be used to finish the dental restoration including an interface for connecting the dental restoration with the prepared tooth.
For example U.S. Pat. No. 6,398,554 discloses a process for the production of a dental prosthesis having a cap for fitting on a human tooth and a crown supported by the cap. The process comprises: taking a digitized three-dimensional image of the tooth; based on the tooth image, defining a digitized internal surface of the prosthesis corresponding to an inner surface of the cap; defining a digitized external surface of the prosthesis, on the basis of environmental parameters of the prosthesis, and taking into account of constraints from the internal surface of the prosthesis; and by use of the internal and external surfaces of the prosthesis, defining an external surface of the cap to form a digitized model of the cap.
US-A-2006/0257824 discloses a method of producing a prosthesis made of a framework as a first component, and a veneer as a second component. The first and second components can be designed by use a CAD system accounting for internal and external surfaces of the prosthesis.
EP application no. 07108206.9 relates to a method of making a veneer for a dental restoration comprising a frame and the veneer. The veneer can be obtained from a veneer precursor made of an open-celled material. An exterior surface of the veneer precursor may be formed based on a virtual model of an exterior surface of the dental restoration. An interior surface of the veneer precursor may be formed based on a virtual model of an exterior surface of a frame. The exterior surface of the dental restoration may be designed on a CAD system by use of surface data obtained from scanning a patient's tooth, scanning a temporary restoration, or scanning a model of a patient's tooth.
There is still a need for a method which provides an efficient workflow for restoring a tooth by use of a separately manufactured dental restoration. It is particularly desirable to minimize and/or efficiently control interactions between the patient, the dentist and the dental technician. A workflow for restoring a tooth should be preferably convenient for the patient. Further such workflow should be time saving and easy to handle for the dentist and the dental technician. It is also desirable to provide a method which provides a precise and optically pleasant dental restoration. Moreover an overall workflow of restoring a tooth and therefore a method of making a dental restoration is preferably relatively inexpensive.